<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>The main interface</title>
    <style type="text/css">

        span {
            border: 5px solid darkseagreen;
            color: lightgray;
            font-size: 30px;
        }
    </style>
</head>
<body>
<span>You have successfully logged in.</span>
<span>Welcome to the main interface.</span>
</body>
</html>